const app = new Vue({
  el: '#app',
  data: {
    books: [
      {
        id: 1,
        name: '《算法导论》',
        date: '2006-9',
        price: 85.00,
        count: 1
      },
      {
        id: 2,
        name: '《Linux编程艺术》',
        date: '2006-2',
        price: 59.00,
        count: 1
      },
      {
        id: 3,
        name: '《编程珠玑》',
        date: '2008-10',
        price: 39.00,
        count: 1
      },
      {
        id: 4,
        name: '《代码大全》',
        date: '2006-3',
        price: 128.00,
        count: 1
      }
    ]
  },
  computed: {
    totalPrice() {
      let totalPrice = 0;
      for(let i = 0; i < this.books.length; i++) {
        totalPrice += this.books[i].count * this.books[i].price;
      }
      return totalPrice;
    }
  },
  methods: {
    getFinalPrice(price) {
      return '￥' + price.toFixed(2);
    },

    decrement(index) {
      console.log('decrement', index);
      this.books[index].count--;
    },

    increment(index) {
      console.log('increment', index);
      this.books[index].count++;
    },

    remove(index) {
      this.books.splice(index, 1);
    }
  },
  filters: {
    showPrice(price) {
      return '￥' + price.toFixed(2);
    }
  }
});